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Sales Enquiries | +61 2 9828 2660


How to choose a Drainage Pit

Here you’ll find some steps you need to go through to ensure you select the correct Pit and Grate/Cover combination.



Every drainage pit is slightly different. Following are some of the key criteria that should be reviewed to choose the best width, length and depth of pit required.

  • Size of Pit – how large is the area? Multiple or single pit?
  • Depth of Pit – pipe depth? Existing or New?
  • Will the pit be used for retention?
  • Any pipe direction change?
  • How many conduits will enter the pit?
  • Any site limitations or other criteria?


Load ratings and environment

  • Is the drainage pit located in a trafficable area? Even if an area isn’t designed for vehicular traffic, it’s important to bear in mind possible delivery vehicles etc.
  • AS3996 is a standard covering load ratings and is a tool to help you choose the correct cover for your application. For information Click Here.
  • Do we require a grate or solid cover? Sewer or Drainage?
  • What will the finished surface look like? Is aesthetics important? Material preference?
  • Will there be a high level of pedestrian traffic? Heelproof? Slip-proof?
  • Where is the project? How strong is the drainage pit for transport; some materials are brittle and not ideal for transport.
  • Any site limitations or other criteria?



  • Compare the installation instructions for various pits bearing in mind the load rating requirements.
  • Depending on loading and surface finish, some polymer, plastic and other materials require special installation. These requirements can greatly affect costs and time on site and in some cases the pit may simply be expensive formwork.
  • Is site access an issue? Product weight may be a concern. Steel reinforced concrete is extremely heavy with no additional benefits.
  • Any site limitations or other criteria?


Access (Safety and security)

  • Do the contents need to be protected from unauthorised entry? Boltdown?
  • Does access pose a security risk?
  • Any site limitations or other criteria?
  • Do the contents need to be protected from the ingress of water?